Custom File Handler for Mainframe Rehosting
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Solution Overview
Problem
Mainframe application rehosting to open systems often results in different behaviors due to platform components, and users may want functionalities not available in the original application, making migration complex and costly.
Innovation Solution
A custom file handler is implemented in the mainframe rehosting platform to intercept file access calls, allowing specific behaviors such as changing file access modes and appending data fields, by providing custom versions of default file operation APIs, which can be invoked by the rehosted application, ensuring transparent interception and injection of special processing operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a mainframe application is rehosted to an open system platform, then cost reduction and agility improvement are achieved, but different functional behaviors occur due to platform component differences
Solution Approach 1:
A custom file handler is introduced as an intermediary layer between the rehosted mainframe application and the open system file operations. This handler includes custom versions of default file operation APIs that intercept file access calls and modify their behavior to match mainframe semantics, thereby maintaining functional consistency while enabling platform migration
Solution Approach 2:
The custom file handler modifies file access parameters and behavior characteristics to bridge the difference between mainframe and open system platforms. By changing how file operations are performed at the API level, the system preserves mainframe application behavior while running on open systems
2Adaptability or versatility
If the original mainframe application code is modified to add new functionalities, then additional capabilities are achieved, but application complexity and modification costs increase
Solution Approach 1:
The custom file handler serves as a mediator that provides enhanced functionalities without requiring changes to the original mainframe application code. By implementing custom versions of file operation APIs, the handler adds capabilities such as modified file access modes and post-handling actions while keeping the application code unchanged
Solution Approach 2:
The file handling functionality is segmented into a separate custom handler component that operates independently from the main application logic. This allows new functionalities to be added to the handler without increasing application code complexity, as the handler acts as a distinct layer
3Adaptability or versatility
If custom file operation APIs are implemented to achieve specific behaviors, then functional flexibility is improved, but system complexity increases
Solution Approach 1:
The custom file handler is designed as a universal component that provides multiple specific behaviors through a single implementation. By creating custom versions of standard file operation APIs, the handler can perform various functions such as changing file access modes, appending data fields, and executing post-handling actions, thereby achieving high versatility without proportionally increasing system complexity
Data Source
AI summary
In accordance with an embodiment, described herein is a system and method for achieving specific behaviors by intercepting file access calls in a mainframe application rehosted in a mainframe rehosting platform. A custom file handler can include a custom version of each of a plurality of default file operation application program interfaces (APIs) available in the mainframe rehosting platform, and can be invoked by the rehosted mainframe application. Each custom file operation API can perform one of a plurality of specific behaviors comprising changing a file access mode, appending a specific data field at the end of each record or line of a file, and performing one or more special post-handling actions. If the rehosted mainframe application cannot detect the existence of a custom file handler, a file access call can be directed to one or more of the plurality of default file operations APIs.